This invention relates to a gas circuit breaker and more particularly a compressed gas circuit breaker employing multi-stage gas blasting about an arc generated by the separation of relatively movable contacts thereby improving the interrupting capacity.
Recently, demand for a circuit breaker with large interrupting capacity and compact size has been increased because of the enlargement of a power system and due to the limited space of installation. Furthermore, it has also been required to provide a simple and accurate circuit breaker construction in view of the cost and the reliability thereof.
In a conventional puffer-type (single gas-flow-type) gas circuit breaker the arc interruption is performed such that an operating rod is first pulled by means of an operating mechanism, and in accordance with the movement of the rod, a cylinder located within an arc extinguishing chamber of the circuit breaker is also moved, whereby the gas in the cylinder is compressed to a high pressure and the compressed gas is blasted through a nozzle part across, or about the arc gererated at the nozzle part thereby interrupting the arc. The breaking efficiency of this type of breaker is determined by the strength of the blasting action. In another conventional double gas-flow-type circuit breaker the blasting efficiency is duplicated in comparison with that of the single gas-flow-type mentioned above. However, in order to obtain a breaking efficiency higher than that of the former type, the latter type must increase the blast pressure or increase the number of serially connected interrupting points. This causes an enlargement in the structural configuration of the circuit breaker and an increase in the driving force which involves much cost making such a breaker uneconomical.